What should be in standard UART

[anukalp]

as far as I know, standard UART has two register transmitter register and receiver register and two flags transmitter flag and receiver flag.

Do uart have shift registers with transmitter register and receiver register?

 

[Harald Kapp]

What do you consider a "standard UART"?
Yes, usually a UART has at least one transmit register and one receive register, but there can also be more than one register per direction, typically organized as FIFOs.
Also you will find registers for setting the operational parameters (baud rate, number of start bits an stop bits, number of bits per word etc.).
As to flags: whatever the designer of the UARTs deemed useful. From a single flag to a complete status register.
You'll have to look up the documentation of the UART you are going to use to see what is offered and match this to your requirements.